1. Technical Field
The present disclosure relates to a method of manufacturing a light emitting device that includes a semiconductor light emitting element and a wavelength conversion layer.
2. Description of the Related Art
Light emitting devices using a semiconductor light emitting element such as a light emitting diode are widely used because of their ease of miniaturization and high light emission efficiency. Light emitting devices using a semiconductor light emitting element are roughly divided into two types, namely, the face up type, in which a semiconductor light emitting element is provided with a pad electrode at a surface on a side opposite to the mounting substrate side, and the face down type, in which the light emitting element is provided with the pad electrode at a lower surface facing the mounting substrate.
With the face down type, the pad electrode provided on the surface of the semiconductor light emitting element and a wiring provided on the mounting substrate can be electrically connected to each other via a connecting member, such as bumps, metal pillars or the like, which are positioned in an area within the outer periphery of the semiconductor light emitting element in a plan view seen from a direction perpendicular to the surface of the mounting substrate. This realizes a chip size package or a chip scale package (CSP) in which the size of the light emitting device (particularly, the size in a plan view seen from a direction perpendicular to the mounting substrate) is reduced almost to the size of a chip of the light emitting element. In recent years, in order to achieve further miniaturization, or in order to further improve the light emission efficiency, face down type light emitting devices have been employed in which a growth substrate (a light-transmissive substrate), made of sapphire or the like, is removed or the thickness of the growth substrate is reduced.
The growth substrate is a substrate for growing thereon an n-type semiconductor layer and a p-type semiconductor layer, which structures the semiconductor light emitting element. The growth substrate also improves the strength of the light emitting device by supporting the semiconductor light emitting element, which has a small thickness and a low mechanical strength. Accordingly, the light emitting device in which the growth substrate is removed or the thickness of the growth substrate is reduced after forming the semiconductor light emitting element, for example, as disclosed in Japanese Patent Application No. JP 2011-258657 A, may be provided with a resin layer on the electrode side (the side opposing the mounting substrate). The resin layer supports the light emitting element. A metal pillar penetrates through the resin layer and electrically connects the electrode of the light emitting element and a wiring (a wiring layer) provided at the mounting substrate. With a resin layer containing a metal pillar, the light emitting device can reliably obtain sufficient mechanical strength.
Meanwhile, for example, JP 2011-258657 A discloses a light emitting device provided with a resin layer that contains a phosphor (a phosphor layer) on the back surface side of the semiconductor light emitting element, i.e., on the side opposite to the resin layer that serves as a base member. The light emitting device is configured such that a portion of light (e.g., a blue light) emitted by a semiconductor light emitting element is converted into a light of a different wavelength (e.g., a yellow light) by the phosphor contained in the resin layer, and the light of the converted wavelength and the light of the unconverted wavelength are mixed to produce a light of a different color (e.g., a white light).
In a light emitting device having such a structure as disclosed in JP 2011-258657 A, the resin layer that serves as a base member is preferably disposed to cover the semiconductor light emitting element in a plan view in order to protect the semiconductor light emitting element from mechanical shock or from the outside air. Also, in such a light emitting device, after the resin layer that serves as a base member is formed on the semiconductor layer side of the semiconductor light emitting element, the growth substrate is peeled off, and the phosphor layer is formed on the side opposite to the resin layer that serves as a base member. At this time, if the phosphor layer is disposed in a shape identical to the resin layer that serves as a base member in a plan view, the phosphor layer is extended to the outer peripheral region of the light emitting device, which is the region outside the semiconductor light emitting element in a plan view. With the phosphor layer extended to the outer peripheral region, emission from the outer peripheral region is mainly a yellow light emitted from the phosphor layer. Accordingly, the color of the light emitted from the light emitting device will have different hues between the region overlapping the semiconductor light emitting element and the outer peripheral region in a plan view. That is, the luminous intensity distribution characteristic of the light emitting device becomes inconsistent. Accordingly, from the viewpoint of the luminous intensity distribution characteristic, it is preferable not to provide the phosphor layer at the outer peripheral region.
JP 2011-258657 A discloses a method of forming the phosphor layer at a predetermined region using a nanoimprinting method or a molding method. Also, JP 2011-258657 A discloses the use of other methods for forming the phosphor layer, such as an inkjet printing method or a dispensing method. However, a nanoimprinting method or a molding method requires an expensive molding assembly. Further, an inkjet printing method and a dispensing method require the application of minute droplets to a predetermined region; thus, in addition to the high price of the application apparatus, high productivity is difficult to achieve.